PDFBox和Itext是操作PDF文档最常用的两种java library。

这里记录一下用两种内库给pdf添加水印的方法。

Itext

import com.itextpdf.text.Document;
import com.itextpdf.text.DocumentException;
import com.itextpdf.text.Image;
import com.itextpdf.text.Paragraph;
import com.itextpdf.text.pdf.PdfContentByte;
import com.itextpdf.text.pdf.PdfReader;
import com.itextpdf.text.pdf.PdfStamper;
import com.itextpdf.text.pdf.PdfWriter;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;

/**
 * Title：ItextPdfUtil
 *
 * @author Flicker
 **/
public class ItextPdfUtil {
    //创建一个pdf文件
    public static void createPdf(){
        Document document = new Document();
        try {
            PdfWriter.getInstance(document,new FileOutputStream("d:\\createPdf.pdf"));
        } catch (DocumentException e) {
            e.printStackTrace();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        document.open();
        try {
            //设置文档文字
            document.add(new Paragraph("Hello world"));
        } catch (DocumentException e) {
            e.printStackTrace();
        }
        document.close();
    }
    //给pdf添加水印
    public static void setImage(){
        try {
            PdfReader reader = new PdfReader("d:\\createPdf.pdf");
            PdfStamper stamper = new PdfStamper(reader,new FileOutputStream("d:\\setWatermarkPdf.pdf"));
            Image image = Image.getInstance("d:\\test\\BarCode.png");
            image.setAbsolutePosition(260,790);
            PdfContentByte under = stamper.getUnderContent(1);
            under.addImage(image);

            stamper.close();
            reader.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        //createPdf();
        setImage();
    }
}

PdfBox

package com.zo.util;

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.rendering.PDFRenderer;

import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;

/**
 * Title：PdfBoxUtil
 *
 * @author Flicker
 **/
public class PdfBoxUtil {
    private static final int LogoPart = 4;

    //pdf转成image
    public static void toImage(){
        File file = new File("d:\\1.pdf");
        try {
            PDDocument doc = PDDocument.load(file);
            PDFRenderer renderer = new PDFRenderer(doc);
            int pageCount = doc.getNumberOfPages();
            for (int i = 0; i < pageCount; i++) {
                // 方式1,第二个参数是设置缩放比(即像素)
                //BufferedImage image = renderer.renderImageWithDPI(i, 296);
                // 方式2,第二个参数是设置缩放比(即像素)
                BufferedImage image = renderer.renderImage(i, 2.5f);
                ImageIO.write(image, "PNG", new File("d:\\1.png"));
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * 给图片添加水印、可设置水印图片旋转角度
     *
     * @param iconPath 水印图片路径
     * @param srcImgPath 源图片路径
     * @param targerPath 目标图片路径
     * @param degree 水印图片旋转角度
     * @param width 宽度(与左相比)
     * @param height 高度(与顶相比)
     * @param clarity 透明度(小于1的数)越接近0越透明
     */
    public static void waterMarkImageByIcon(String iconPath, String srcImgPath,
                                            String targerPath, Integer degree, Integer width, Integer height,
                                            float clarity) {
        OutputStream os = null;
        try {
            Image srcImg = ImageIO.read(new File(srcImgPath));

            System.out.println("width:" + srcImg.getWidth(null));
            System.out.println("height:" + srcImg.getHeight(null));

            BufferedImage buffImg = new BufferedImage(srcImg.getWidth(null),
                srcImg.getHeight(null), BufferedImage.TYPE_INT_RGB);
            // 得到画笔对象
            // Graphics g= buffImg.getGraphics();
            Graphics2D g = buffImg.createGraphics();
            // 设置对线段的锯齿状边缘处理
            g.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
                RenderingHints.VALUE_INTERPOLATION_BILINEAR);
            g.drawImage(
                srcImg.getScaledInstance(srcImg.getWidth(null),
                    srcImg.getHeight(null), Image.SCALE_SMOOTH), 0, 0,
                null);
            if (null != degree) {
                // 设置水印旋转
                g.rotate(Math.toRadians(degree),
                    (double) buffImg.getWidth() / 2,
                    (double) buffImg.getHeight() / 2);
            }

            // 水印图象的路径 水印一般为gif或者png的，这样可设置透明度
            ImageIcon imgIcon = new ImageIcon(iconPath);
            // 得到Image对象。
            Image img = imgIcon.getImage();
            float alpha = clarity; // 透明度
            g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP,
                alpha));

            // 表示水印图片的位置
            g.drawImage(img, width, height, null);
            g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER));
            g.dispose();
            os = new FileOutputStream(targerPath);
            // 生成图片
            ImageIO.write(buffImg, "JPG", os);
            System.out.println("添加水印图片完成!");
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (null != os) {
                    os.close();
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    public static void main(String[] args) {
        //toImage();
        waterMarkImageByIcon("d:\\test\\BarCode.png","d:\\1.png","d:\\2.png"
            ,0,1000,10,1f);
    }
}